A Horizontal and a Vertical Control Operator plot coordinates on a paper in Korea during the Korean War.

U.S. Marine Corps of Kimpo Provisional Regiment in Korea during the Korean War. Interior of a FDC (Fire Direction Center) bunker. U.S. soldiers relax, sit around and read prior to a fire mission. A wall map in the background. A man answers a phone. A Horizontal Control Operator (HCO) and a Vertical Control Operator (VCO) look up they grab their pads and take down data from an FO (Forward Observer). The HCO plots coordinates. He looks up and speaks to a computer. A view of the hands of the HCO as he plots the coordinates. The VCO plots the coordinates. A close up of the VCO plotting the coordinates and he calls out to the computer. The VCO picks up a phone and speaks to the Battery Executive in the field. A forward observer phone operator speaks over a phone and starts timing with his watch. The watch and the man on the phone.